Quantity   Component name
1 × Set of four Vex Mecanum wheels http://www.vexrobotics.com/vex/products/accessories/motion/276-1447.html
1 × Four motor, four quadrature encoder version of Dagu's Rover 5 https://www.sparkfun.com/products/10336
1 × Propeller QuickStart http://www.parallax.com/product/40000
2 × L298N H-bridge with PCB and snubber diodes (don't pay more than $3 for one) http://www.ebay.com/itm/Dual-H-Bridge-DC-Stepper-Motor-Drive-Controller-Board-Module-Arduino-L298N-HG-/281551893660?pt=LH_DefaultDomain_0&hash=item418dccf49c